Overview. The total weight of the body is transmitted through the ankle to the foot. The ankle and foot must balance the body and absorb the impact of the heel strike and gait. Despite thick padding along the toes, sole, and heel and stabilizing ligaments at the ankles, the ankle and foot are frequent sites of sprain and bony injury.
The ankle is a hinge joint formed by the tibia, the fibula, and the talus. The tibia and fibula act as a mortise, stabilizing the joint while bracing the talus like an inverted cup.
The principal joints of the ankle are the tibiotalar joint, between the tibia and the talus, and the subtalar (talo-calcaneal) joint.
Note the principal landmarks of the ankle: the medial malleolus, the bony prominence at the distal end of the tibia, and the lateral malleolus, at the distal end of the fibula. Lodged under the talus and jutting posteriorly is the calcaneus, or heel.
An imaginary line, the longitudinal arch, spans the foot, extending from the calcaneus of the hind foot along the tarsal bones of the midfoot (see cuneiforms, navicular, and cuboid bones below) to the forefoot metatarsals and toes. The heads of the metatarsals are palpable in the ball of the foot. In the forefoot, identify the metatarsophalangeal joints, proximal to the webs of the toes, and the proximal and distal interphalangeal joints of the toes.
Structures. Movement at the ankle joint is limited to dorsiflexion and plantar flexion. Plantar flexion is powered by the gastrocnemius, the posterior tibial muscle, and the toe flexors. Their tendons run behind the malleoli. The dorsiflexors include the anterior tibial muscle and the toe extensors. They lie prominently on the anterior surface, or dorsum, of the ankle, anterior to the malleoli.
Ligaments extend from each malleolus onto the foot. Medially, the triangle-shaped deltoid ligament fans lateral view
out from the inferior surface of the medial malleolus to the talus and proximal tarsal bones, protecting against stress from eversion (ankle bows inward). The three ligaments on the lateral side are less substantial, with higher risk of injury: the anterior talofibular ligament—most at risk in injury from inversion (ankle bows outward) injuries; the calcaneofibular ligament; and the posterior talofibular ligament. The strong Achilles tendon inserts on the heel posteriorly.
H Changes With Aging_
Musculoskeletal changes continue through the adult years. Soon after maturity adults begin to lose height subtly, and significant shortening becomes obvious in old age. Most loss of height occurs in the trunk as intervertebral discs become thinner and the vertebral bodies shorten or even collapse because of osteoporosis. Flexion at the knees and hips may contribute to shortened stature. The limbs of an elderly person thus tend to look long in proportion to the trunk.
The alterations in discs and vertebrae contribute too to the kyphosis of aging and increase the anteroposterior diameter of the chest, especially in women.
With aging, skeletal muscles decrease in bulk and power, and ligaments lose some of their tensile strength. Range of motion diminishes, partly because of osteoarthritis.
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